It quite often appears following rainfall at the start of the drying process, as the outline of the block shows the differing levels of absorbency of the masonry and its bedding mortar.
In order to prevent ghosting, careful consideration should be given to what thickness of render is used.
The location, orientation and surrounding environment of the building to be rendered, as well as exposure to wind and rain, along with potential protection from surrounding buildings all have an impact on the thickness required to protect the build.
For sheltered to moderate exposure, the minimum recommended thickness of render is 15mm, and this rises to 20mm in the case of severe exposure.
The visual impact of ghosting is worsened in new construction, if the building components have not dried out fully.
If this is the case, the effect should lessen over time – Saint-Gobain Weber recommend leaving the render for a couple of months, in the hope once the blocks are fully dry, and the render fully cured, ghosting will no longer be issue.
If after waiting, the problem persists, there are two options to remedy it…
A high-performance, water-resistant paint, such as webersil P, may be applied to the building to overcome the issue of ghosting. webersil P is a mineral paint with exceptional long-term durability and performance, and comes in a range of 160 colours. This paint is suitable for use with our weberpral renders, provided the elevation is clean, sound and dry.
In some circumstances, it may be advisable that rather than painting, the thickness of the render should be increased.
Before re-rendering, the entire area to be rendered should be stripped of any paint or coating, and should be clean, dry and sound.
If necessary, a coat of weber CL150 can be used to ensure no algae is present on the surface. A keycoat of weberend aid should be applied, followed by a pass of weberpral M (or weberpral D in Ireland) render at 10mm which is scraped back to a thickness of 6mm.
As with any project, Saint-Gobain Weber will be with you every step of the way. If you’ve unexpectedly experienced ghosting, the company is happy to advise on how best to deal with the issue.
Dickens House, Enterprise Way
Geometrically-shaped with many facets, the roofs of Thorpepark Academy in Hull now have a guaranteed extra 20 years of life after being fitted with a cost-effective overlay system devised by AHR consultants and BMI.Posted in Articles, Building Industry News, Building Products & Structures, Case Studies, Insulation, Restoration & Refurbishment, Retrofit & Renovation, Roofs
The GGF recently attended the Government Work Stream on RMI (Repair Maintenance and Improvement) and raised several issues on behalf of GGF Members and the wider industry.Posted in Articles, Building Associations & Institutes, Building Industry News, Building Products & Structures, Glass, Glazing, news, Posts, Windows
Leading construction and infrastructure player Aggregate Industries completed the surfacing works ahead of schedule on the M23 smart motorway project.Posted in Articles, Building Industry News, Building Products & Structures, Case Studies, Civil Engineering, Concrete, Cement, Admixtures, Hard Landscaping & Walkways, Landscaping, Restoration & Refurbishment, Retrofit & Renovation
Installers using TommyTrinder.com’s pioneering sales and visualisation app have given its support service a 5-star average rating.Posted in Articles, Building Industry News, Building Products & Structures, Information Technology, Restoration & Refurbishment, Retrofit & Renovation, Windows